Virtual machines: before and after

It’s time to drag our virtual machine platform into the 21st century and we’ve started to see the results today:

This disjoint graph shows the total load on one of our ordinary virtual machine servers, about as heavily loaded as we allow them to get.  On the left we can see a couple of days ordinary load with spikes and relatively wide variation in responsiveness.  On the right, that’s exactly the same set of virtual machines, on identical hardware, after being copied on our new platform and started up again (I omitted out the load ramp-up and ramp-down as we copied).  That’s quite a big difference, and I suspect the customers with VMs on the server can feel it.  I’m being a little guarded at the moment: we’re not quite done tweaking bits of the system and the emulator will need rebuilding a few more times before we’re completely happy with it (the "emulator" is KVM, not Xen, and I’m more than happy with its advantages).  Assuming nothing goes terribly wrong in the next couple of weeks we’ll continue this roll-out and conversion of our customers’ systems, and our customers systems will get a fair amount faster, for free.  This is a good thing.  More for less.  Applause.

That’s not the half of it, but the core performance improvement felt worth a glib graph.  The marketing demon on my shoulder is shushing me now.  Also saying we’re out of fizzy drinks.